1. Field of the Invention
This invention relates to a semiconductor laser device.
2. Background Art
Nitride semiconductors emitting blue-violet laser light have high melting point and high equilibrium vapor pressure of nitrogen, interfering with their bulk crystal growth from melt. Hence it is difficult to use a large-diameter GaN substrate for epitaxial growth of a nitride semiconductor laminated body including a light emitting layer, resulting in a low yield of semiconductor laser chips per wafer. Chip downsizing is required for increasing the chip yield. However, simply decreasing the optical resonator length results in increased current density and is likely to cause degradation due to heat generation. Hence reduction of current density including reduction of threshold current is required.
JP 2002-094190A discloses a technique concerning a nitride semiconductor light emitting device in which the threshold current is reduced by effectively confining light in the light emitting layer. In this technique, the threshold current is reduced by setting the thickness of the p-type cladding layer to less than 0.3 μm, thereby cutting off higher order modes in the vertical transverse mode.